[gcc r13-1618] [Ada] Fix missing Overflow and Range checks

[gcc r13-1618] [Ada] Fix missing Overflow and Range checks

[Pierre-Marie de Rodat]

https://gcc.gnu.org/g:1ef1ac768ff108a6a2c08e18eec3309e182df142

commit r13-1618-g1ef1ac768ff108a6a2c08e18eec3309e182df142
Author: Marc Poulhiès <poulhies@adacore.com>
Date:   Fri Jun 17 16:07:35 2022 +0200

    [Ada] Fix missing Overflow and Range checks
    
    While doing Preanalysis (as is the case during ghost code handling),
    some range and/or overflow checks can be saved (see Saved_Checks in
    checks.adb) and later one omitted as they would be redundant (see
    Find_Check in checks.adb). In the case of ghost code, the node being
    Preanalyzed is a temporary copy that is discarded, so its corresponding
    check is not expanded later. The node that gets expanded later is not
    having any checks expanded as it is wrongly assumed it has already been
    done before.
    
    As is already the case in Preanalyze_And_Resolve, this change suppresses
    all checks during Preanalyze except for GNATprove mode.
    
    gcc/ada/
    
            * sem.adb (Preanalyze): Suppress checks when not in GNATprove
            mode.
            * sem_res.adb (Preanalyze_And_Resolve): Add cross reference in
            comment to above procedure.
            * sinfo.ads: Typo fix in comment.

Diff:
---
 gcc/ada/sem.adb     | 10 +++++++++-
 gcc/ada/sem_res.adb |  8 +++++---
 gcc/ada/sinfo.ads   |  6 +++---
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/gcc/ada/sem.adb b/gcc/ada/sem.adb
index 796fffb3065..6c1e9d7eb01 100644
--- a/gcc/ada/sem.adb
+++ b/gcc/ada/sem.adb
@@ -1338,7 +1338,15 @@ package body Sem is
       Full_Analysis := False;
       Expander_Mode_Save_And_Set (False);
 
-      Analyze (N);
+      --  See comment in sem_res.adb for Preanalyze_And_Resolve
+
+      if GNATprove_Mode
+        or else Nkind (Parent (N)) = N_Simple_Return_Statement
+      then
+         Analyze (N);
+      else
+         Analyze (N, Suppress => All_Checks);
+      end if;
 
       Expander_Mode_Restore;
       Full_Analysis := Save_Full_Analysis;
diff --git a/gcc/ada/sem_res.adb b/gcc/ada/sem_res.adb
index 3ff0afd1712..1053cec6dd2 100644
--- a/gcc/ada/sem_res.adb
+++ b/gcc/ada/sem_res.adb
@@ -2046,16 +2046,18 @@ package body Sem_Res is
       Full_Analysis := False;
       Expander_Mode_Save_And_Set (False);
 
+      --  See also Preanalyze_And_Resolve in sem.adb for similar handling
+
       --  Normally, we suppress all checks for this preanalysis. There is no
       --  point in processing them now, since they will be applied properly
       --  and in the proper location when the default expressions reanalyzed
       --  and reexpanded later on. We will also have more information at that
       --  point for possible suppression of individual checks.
 
-      --  However, in SPARK mode, most expansion is suppressed, and this
-      --  later reanalysis and reexpansion may not occur. SPARK mode does
+      --  However, in GNATprove mode, most expansion is suppressed, and this
+      --  later reanalysis and reexpansion may not occur. GNATprove mode does
       --  require the setting of checking flags for proof purposes, so we
-      --  do the SPARK preanalysis without suppressing checks.
+      --  do the GNATprove preanalysis without suppressing checks.
 
       --  This special handling for SPARK mode is required for example in the
       --  case of Ada 2012 constructs such as quantified expressions, which are
diff --git a/gcc/ada/sinfo.ads b/gcc/ada/sinfo.ads
index a9099e3a0d9..ddac1c92834 100644
--- a/gcc/ada/sinfo.ads
+++ b/gcc/ada/sinfo.ads
@@ -554,9 +554,9 @@ package Sinfo is
    --  The tree after this light expansion should be fully analyzed
    --  semantically, which sometimes requires the insertion of semantic
    --  preanalysis, for example for subprogram contracts and pragma
-   --  check/assert. In particular, all expression must have their proper type,
-   --  and semantic links should be set between tree nodes (partial to full
-   --  view, etc.) Some kinds of nodes should be either absent, or can be
+   --  check/assert. In particular, all expressions must have their proper
+   --  type, and semantic links should be set between tree nodes (partial to
+   --  full view, etc.). Some kinds of nodes should be either absent, or can be
    --  ignored by the formal verification backend:
 
    --      N_Object_Renaming_Declaration: can be ignored safely